严格走样C或C ++的事情吗？

问题描述

在ISO / IEC 9899：TC2，标准说，以下

So, it is not clear from the standard that a pointer of one type can be casted to pointer of another type.

解决方案

Strict aliasing rule is defined somewhere else. This is the wording:

C (ISO/IEC 9899:1999 6.5/7):

C++ (ISO/IEC 14882:2011 3.10 [basicl.lval] / 15):

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The C standard doesn't prohibit you from casting the pointer to an unrelated type, provided there are no allignment problems. However, due to the strict aliasing rule, you basically can't dereference a pointer obtained from such a cast. So the only useful thing to do with such "invalid" pointer is to cast it back to the correct type (or a compatible type).

It's mostly the same in C++ with reinterpret_cast (5.2.10 [expr.reinterpret.cast] / 7):

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